PROJECT SUMMARY In the United States, severe maternal morbidity (SMM) has increased nearly 200% in the past two decades, reaching a rate of 146 out of 10,000 births in 2015 according to a recent report from the Agency for Healthcare Research and Quality (AHRQ). U.S. maternal mortality remains among the highest of all developed countries. Approximately 52,000 U.S. women per year experience SMM, defined as a pregnancy complication that causes significant adverse consequences for the woman or puts her at risk of death. SMM disproportionately affects women from racial and ethnic minority groups, residents of low-income zip codes, and those with Medicaid or no insurance. Although prior research has identified individual-level factors associated with increased risk of maternal mortality and SMM such as age, race, and history of chronic disease, these account for only 20-40% of the variation in obstetric complications. Hospital factors at the time of delivery are estimated to account for only another 20% of the variation, suggesting that upstream factors contribute significantly to SMM. One upstream factor is preconception care, which is defined as preventive healthcare a patient receives before pregnancy to address pregnancy-related risk factors. Preconception care has been hailed as a promising strategy to prevent adverse pregnancy outcomes and reduce racial/ethnic disparities in both maternal and infant health, but its benefits for maternal outcomes have not yet been demonstrated. This project will address AHRQ's priority of harnessing data to improve healthcare quality and patient outcomes by using national Medicaid claims data to address key evidence gaps that disproportionately affect low-income women. This study will lay the groundwork for a larger future study testing the causal link between preconception care and maternal outcomes. Medicaid data offer the opportunity to follow millions of women through multiple sites of care over time and observe large numbers of even rare adverse outcomes. We will observe approximately 12 million pregnancies among women enrolled in Medicaid to develop and validate a claims-based measure of preconception care utilization. We will identify the association between preconception care utilization and the risk of SMM among all pregnancies covered by Medicaid and specifically among individuals with chronic diseases. Finally, we will assess the amount of racial/ethnic disparities in SMM attributable to a lack of preconception care. This will lay the groundwork for a future R01 to test the causal relationship between increased access to preconception care and maternal outcomes, which will have direct relevance to healthcare policy and the structure of service delivery.